Mobile terminals residing in a mobile network and being served through a circuit switched connection may request a packet data network connection e.g. in a context of requesting access e.g. to Internet or to a private data network. The packet data network connection may be established via a GPRS (General Packet Radio Service) or an EPS (Evolved Packet System) network, which are commonly known implementations for providing packet based data services for subscribers. The GPRS or EPS network may accept the request or reject the request. In case the network rejects the request it is desirable that the mobile refrains from further futile attempts to establish the connection in order to avoid unnecessary utilization of network resources.
The network may, depending on the reason for rejection, force the mobile terminal to back-off further attempts for a network defined time period. To control the mobile terminal's behavior the GPRS or EPS network may add a so called “back-off timer” in the reject message, together with other parameters in the message, e.g. the cause code which indicates the reason why the rejection occurs. In this manner the network may control the utilization of network resources efficiently.
Another aspect to mobile communication is that one or more operators are offering telecommunication services through networks in a certain area. The operator networks, i.e. PLMNs (public land mobile network), are arranged to be identifiable by means of a so called mobile network code (MNC) when used together with a mobile country code (MCC). The MNC is an identifier assigned to a network, and thus for a telecom operator, and which comprises a predetermined number of digits, such as three in Europe. Depending on the network implementation the telecom operator may use only a single mobile network code for the operator network managed by the telecom operator in question or multiple mobile network codes for the operator network, which are managed by the telecom operator in question. The multiple mobile network codes are considered equivalent in view of a mobility functionality of a mobile terminal. The mobility functionality covers at least handover aspects, cell reselection aspects and PLMN selection aspects.
In case a network operator uses multiple mobile network codes, and those mobile network codes are equivalent, the back-off conditions apply only for one mobile network code and packet data network (Access Point name), and not for the other equivalent mobile network codes. The mobile terminals move frequently between cells in the mobile networks, which results in them accessing the mobile operator network using different mobile network codes. It is in some networks desired that the mobile terminals would refrain from resetting the back-off condition when they move between cells where different mobile network codes are used.
For example, imagine a train carrying several hundred mobile terminals into a network cell and out of a network cell in a short time span and wherein the cell and its adjacent cells are configured with different mobile network codes. Unless the back-off condition is maintained during the change between the mobile network codes used in the different cells, all mobile terminals on the train may attempt to establish the futile packet data connections simultaneously. Futile mass connection attempts have a negative impact on user experience and system load, which also impacts users that are not part of the mass attempts.
Hence, there is need for managing attempts to establish a packet data network connection especially in an environment wherein equivalent PLMNs using different mobile network codes are available for a mobile terminal.